Littelfuse Launches AK-FL TVS Diodes with Flat Clamping for Aviation Power Systems

Littelfuse has launched the AK-FL Series FlatSuppressX TVS diodes for transient protection in high-voltage aviation and eVTOL power systems.

Available with 6 kA, 8 kA and 10 kA surge current ratings at an 8/20 µs waveform, the axial-leaded devices are intended for DC power rails and solid-state power controller (SSPC) circuits operating within 270 V to 800 V DC aviation power architectures.

The main difference from a conventional TVS diode is the way the AK-FL Series behaves as surge current increases. Littelfuse's FlatSuppressX technology uses a foldback/snapback I-V characteristic designed to maintain a relatively flat, low clamping voltage during fast transients and high-energy surge events.

Keeping the Clamping Voltage Under Control

A conventional TVS diode begins conducting when a transient exceeds its breakdown region, but its clamping voltage continues to increase as surge current rises. That relationship can become important when the components downstream of the TVS have a limited voltage margin.

FlatSuppressX takes a different approach. Its foldback characteristic is designed to keep the clamping voltage more stable as the device conducts higher surge currents. Littelfuse developed the AK-FL Series around this behavior to protect SSPC modules and other semiconductor devices used on high-voltage aircraft DC power rails.

Keeping the clamping voltage lower also gives designers more room between the normal operating voltage of the power system and the maximum voltage experienced by the protected semiconductor during a transient. Littelfuse says this can provide greater flexibility when selecting the voltage rating of downstream devices.

6 kA to 10 kA Surge Protection for Aviation

The AK-FL family is offered in three surge current ratings of 6 kA, 8 kA and 10 kA, specified using an 8/20 µs current waveform. This gives designers several levels of transient protection within the same FlatSuppressX family.

Littelfuse is targeting aerospace and defense power systems, SSPC circuits, eVTOL platforms and other high-reliability avionics applications. Each device is 100 percent screened using MIL-STD-750 test methods, including visual inspection, surge testing, temperature cycling and high-temperature reverse bias (HTRB).

The series is also designed to support RTCA DO-160 environmental qualification requirements for avionics applications.

AK-FL devices use an axial-leaded package that supports both reflow and wave soldering. The package is halogen-free, RoHS compliant and uses Pb-free E4 termination.

The AK-FL Series is available now, with samples available through authorized Littelfuse distributors.

Learn more and read the original announcement at littelfuse.com.

Technology Overview

The Littelfuse AK-FL Series is a family of axial-leaded FlatSuppressX TVS diodes for high-voltage aviation and eVTOL power systems. The devices use a foldback/snapback I-V characteristic to maintain a relatively flat clamping voltage and are available with 6 kA, 8 kA and 10 kA surge current ratings at 8/20 µs.

FAQs

What is Littelfuse FlatSuppressX technology?

FlatSuppressX uses a foldback/snapback I-V characteristic designed to maintain a relatively flat, low clamping voltage during transient events, including at high surge currents.

What surge current ratings are available in the AK-FL Series?

The AK-FL Series is available with 6 kA, 8 kA and 10 kA surge current ratings, specified using an 8/20 µs waveform.

Where are AK-FL TVS diodes intended to be used?

Littelfuse is targeting 270 V to 800 V DC aviation power systems, including SSPC circuits, eVTOL electrical systems and DC power rail protection in high-reliability avionics.